1. Field of the Invention
The present invention relates to an optical pickup and so on used for an information processing apparatus for optically performing recording, reproduction, erasure and so on of information.
2. Related Art of the Invention
In the case of recording and reproducing on a plurality of record media for recording and reproducing at different wavelengths respectively by a single apparatus, an optical pickup having a plurality of light sources of different wavelengths according to the types of the record media is generally used. FIG. 9 shows a configuration of the optical pickup in the past. Reference numerals 901 and 902 denote light source units of mutually different wavelengths, and though it is not shown, they are comprised of, for instance, a semiconductor laser, a hologram, a photo-detector and so on that are examples of the light sources as one piece. The light emitted from the light source unit 901 passes through a beam splitter (hereinafter, BS) 903, and then it is condensed on a record medium 905 by a condenser lens 904. The light reflected by the record medium 905 enters into the light source unit 901 by following a reverse optical path. The light incident on the light source unit 901 is diffracted by the hologram built into the light source unit, and various signals including focus, tracking and RF are detected by the photo-detector in the light source unit. However, the configuration of the inside of the light source units 901 and 902 and methods of detecting various signals are not substantial components of this technology and the present invention described hereafter, and also various configurations are already in the public domain, so that description thereof will be omitted.
The light emitted from the light source unit 902 is reflected by the BS 903 and then is condensed on the record medium 905 by the condenser lens 904. The light reflected by the record medium 905 enters into the light source unit 902 by following the reverse optical path, and the various signals are detected as with the light source unit 901. The BS 903 synthesizes and separates the lights from the light source units 901 and 902, where a band-pass filter for controlling reflection and transmission of the lights by the wavelength, a polarizing beam splitter for controlling them by polarization, a half mirror for separating them into a transmitted light and a reflected light at an arbitrary ratio and so on are generally used. The light source units 901 and 902 are connected to a drive circuit 906 and a control circuit 907, a drive circuit 908 and a control circuit 909 respectively, and the drive circuit supplies a current to the semiconductor laser that is the light source in the light source unit according to the signal from the control circuit so as to control light emission.
As this configuration in the past has the drive circuit and the control circuit provided to each light source unit, there are large amounts of circuitry in the entire optical pickup so that it has problems such as increased costs and upsizing of the apparatus.
An object of the present invention is to implement an optical pickup and so on for driving a plurality of light sources with a small amount of circuitry and having high-performance drive characteristics.
One aspect of the present invention is an optical pickup for recording and reproducing information on a plurality of record media respectively, said pick up having:
a plurality of light sources corresponding to said plurality of record media;
a drive circuit of driving one of said plurality of light sources;
switching means of switching a connection between said drive circuit and one of said plurality of light sources; and
a control circuit of controlling said drive circuit and said switching means, and wherein:
as for transmission line lengths between said switching means and said plurality of light sources, the shorter a wavelength of the light source is, the shorter the transmission line length thereof is.
Another aspect of the present invention is an optical pickup for recording and reproducing information on a plurality of record media respectively, said pickup having:
a plurality of light sources corresponding to said plurality of record media;
a plurality of drive circuits of driving said plurality of light sources respectively;
switching means of switching a signal from the outside to one of said drive circuits and outputting it; and
a control circuit of controlling said drive circuits and said switching means, and wherein:
as for transmission line lengths between said switching means and said plurality of light sources, the shorter a wavelength of the light source is, the shorter the transmission line length thereof is.
Still another aspect of the present invention is the optical pickup, wherein, when the wavelength of the light source of the shortest wavelength, of said plurality of light sources, is xcex1 and the wavelengths of the other light sources are xcex2, xcex3, . . . xcexn (n=2, 3, 4 . . . ) in increasing order of wavelength, and the transmission line lengths between said plurality of light sources and said switching means are L1, L2, L3, . . . Ln in increasing order of wavelength, there is a relationship, between the wavelengths and the transmission line lengths, of L1/L2 less than xcex1/xcex2, L1/L3xe2x89xa6xcex1/xcex3, . . . L2/Lnxe2x89xa6xcex1/xcexn.
Yet still another aspect of the present invention is an optical pickup having:
a first light source of recording or reproducing information on a record medium;
a second light source of reproducing the information from said record medium;
a drive circuit of driving said first light source or second light source;
switching means of switching a connection between said drive circuit and said first light source or second light source; and
a control circuit of controlling said drive circuit and said switching means, and wherein:
a transmission line length between said switching means and said first light source is shorter than that between said switching means and said second light source.
Still yet another aspect of the present invention is an optical pickup having:
a first light source of recording or reproducing information on a record medium;
a second light source of reproducing the information from said record medium;
a first drive circuit of driving said first light source;
a second drive circuit of driving said second light source;
switching means of switching a signal from the outside to said first drive circuit or said second drive circuit and outputting it; and
a control circuit of controlling said first drive circuit, said second drive circuit and said switching means, and wherein:
a transmission line length between said switching means and said first light source is shorter than that between said switching means and said second light source.
A further aspect of the present invention is the optical pickup, wherein said first light source is plurality of light sources corresponding to a plurality of record media, and as for transmission line lengths between said switching means and said plurality of light sources, the shorter a wavelength of the light source is, the shorter the transmission line length thereof is.
A still further aspect of the present invention is the optical pickup, wherein, when the wavelength of the light source of the shortest wavelength, of said plurality of light sources, is xcex1 and the wavelengths of the other light sources are xcex2, xcex3, . . . xcexn (n=2, 3, 4 . . . ) in increasing order of wavelength, and the transmission line lengths between said plurality of light sources and said switching means are L1, L2, L3, . . . Ln in increasing order of wavelength, there is a relationship, between the wavelengths and the transmission line lengths, of L1/L2xe2x89xa6xcex1/xcex2, L1/L3xe2x89xa6xcex1/xcex3, . . . L1/Lnxe2x89xa6xcex1/xcexn.
A yet further aspect of the present invention is the optical pickup, wherein said drive circuit and said switching means are configured as one piece.
A still yet further aspect of the present invention is the optical pickup, wherein said light sources and said switching means are configured as one piece.
An additional aspect of the present invention is the optical pickup, wherein said n is 2 or 3.
A still additional aspect of the present invention is an information processing apparatus having:
an optical pickup according to any of 1st to 10th inventions;
demodulation means of demodulating a signal obtained from said optical pickup; and
modulation means of modulating the signal to be outputted to said optical pickup.
A yet additional aspect of the present invention is an optical information recording and reproducing method of recording and reproducing information on a plurality of record media respectively, said method having:
a driving step of driving any one of a plurality of light sources corresponding to said plurality of record media;
a switching step of switching a connection of any one of said plurality of light sources in said driving step; and
a controlling step of controlling said driving step and said switching step, and wherein:
as for transmission line lengths of said plurality of light sources in said switching step, the shorter a wavelength of the light source is, the shorter the transmission line length thereof is.
A still yet additional aspect of the present invention is an optical information recording and reproducing method of recording an reproducing information on a plurality of record media respectively, said method having:
a plurality of driving steps of driving a plurality of light sources corresponding to said plurality of record media respectively;
a switching step of switching a signal from the outside to one of said driving steps and using it; and
a controlling step of controlling said driving step and said switching step, and wherein:
as for transmission line lengths of said plurality of light sources in said switching step, the shorter a wavelength of any one of said plurality of light sources is, the shorter the transmission line length thereof is.
A supplementary aspect of the present invention is the optical information recording and reproducing method, wherein, when the wavelength of the light source of the shortest wavelength, of said plurality of light sources, is xcex1 and the wavelengths of the other light sources are xcex2, xcex3 . . . xcexn (n=2, 3, 4 . . . ) in increasing order of wavelength, and the transmission line lengths of said plurality of light sources are L1, L2, L3, . . . Ln in increasing order of wavelength thereof, there is a relationship, between the wavelengths and the transmission line lengths, of L1/L2xe2x89xa6xcex1/xcex2, L1/L3xe2x89xa6xcex1/xcex3, . . . L1/Lnxe2x89xa6xcex1/xcexn.
A still supplementary aspect of the present invention is an optical information recording and reproducing method having:
a driving step of driving a first light source for recording or reproducing information on a record medium and a second light source for reproducing the information from said record medium;
a switching step of switching said first light source or second light source in said driving step; and
a controlling step of controlling said driving step and said switching step, and wherein:
a transmission line length of said first light source in said switching step is shorter than that of said second light source.
A yet supplementary aspect of the present invention is an optical information recording and reproducing method having:
a first driving step of driving a first light source for recording or reproducing information on a record medium;
a second driving step of driving a second light source for reproducing the information from said record medium;
a switching step of switching a signal from the outside to said first driving step or said second driving step and outputting it; and
a controlling step of controlling said first driving step, said second driving step and said switching step, and wherein:
a transmission line length of said first light source in said switching step is shorter than that of said second light source.
Thus, it is become possible to drive a plurality of light sources with small amounts of circuitry and to implement excellent driving characteristics.
And, they have an effect that makes possible to drive a plurality of light sources with small amounts of circuitry. Moreover, by configuring switching means and driving circuit or light source as one piece, it possible to miniaturize, to make low cost and to make high quality an optical pickup and an information processing apparatus.